Inkscape -> dxf -> KiCad

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  1. Make a picture of the existing pcb, outline.
  2. Scale photo according the feature you measured. (In my example I put a rectangle with sides of 76×35 in [mm] millimetres and resize datasheet photo of enclosure with locked ratio to this rectangle.)
  3. Throw simple shapes on holes and other important features, by drawing object, straight lines or curves.
  4. Straight lines don’t need conversion, but objects and curves do.
  5. Transform objects like this example circles to path: Path -> Object to Path
  6. Transform paths/curves to straight lines: select curves and use Apply Extensions > Modify Path > Flatten Bezier (selecting lower value increases number of segments)
  7. then save a copy as DXF, define the Base unit (I picked/worked in [mm] )
  8. in KiCad goto File -> Import -> DXF, find file and apply it to wanted layer  (example with enclosure features and added low segment circle)

inkscape_to_kicad-1 inkscape_to_kicad-2 inkscape_to_kicad-3inkscape_to_kicad-4inkscape_to_kicad-5inkscape_to_kicad-6 inkscape_to_kicad-7inkscape_to_kicad-8inkscape_to_kicad-9inkscape_to_kicad-10inkscape_to_kicad-11inkscape_to_kicad-12

Written by luftek

September 19th, 2016 at 10:46 pm

Posted in Make,pcb

Tagged with ,

Operational and instrumentation amplifiers (OPA2333, OPA333, INA333)

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A friend approached me to check if I could make his circuit work.
Bunch of wires all over the breadboard (sorry no photo) with OPA2333, OPA333, INA333 on it. :)
Most too long to see, some broken off and a short on pin 7 and 8 on INA333.

2016-08-12-16_17_06-ina333-pdf-adobe-reader img_20160811_173748

Steps to a working circuit?

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Written by luftek

August 12th, 2016 at 6:49 pm

Posted in Make

LimeSDR enclosure, PCB – front and rear panel

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sample_v3_assembly (3) present_kit


I forked LimeSDR repo on Github for the purpose of enclosure:
Now I sent two PCB panels to owners (I am waiting for mine from Crowdsupply)Probably not good regarding EMI (Electromagnetic Interference) as it is aluminium shell, which is also painted (isolation). But is good as mechanical protection.I decided for 97x40x100, but enclosures of 76x35x100 are easier to come by and more portable. Maybe also try smaller version.GitHub:

update 14.8.:
eBay listing did well :) Sold off all of remaining panels from 1st batch in 3 days. Now I have the funds to order for 76x35x100 enclosure

update 6.9.:
76×35 panels came out great, I offer them under same eBay listing, more on new version on GitHub:

Written by luftek

August 10th, 2016 at 3:07 pm

Posted in pcb

Lets have some PCBs made

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me + KiCad + PCB Panelizer Beta + Dirty PCB = great job! for first PCBs after some time


Written by luftek

May 7th, 2016 at 2:59 pm

Posted in Uncategorized

KM switch inside a desktop computer, custom PCB – DRAFT

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KVM switch stands for (Keyboard, Video, Mouse) switch. When wanting to utilize my setup of two 24″ monitors and keyboard + mouse for friends or work laptop I would need to make all connections piece by piece. So VGA, DisplayPort, keyboard and mouse.

Both monitors have 2 connections possible, so using another pair of cables for laptop is convenient. Then just switch video input on monitor.
Transitioning in case of keyboard and mouse is not so.

Currently I have this KVM switch inside my desktop computer. It uses

slike installlacije v računalniku 

Kako bi kit izgledal:




PCB internal:
pcb  front_plate (missing some holes)

Enclosure front plate:



solution similar to

slike nameči v mapo, naredi enostavno skico in sklice na dele.


Shematics of KM part:


Dropbox shared folder:
“project” folder


Written by luftek

March 2nd, 2016 at 10:28 pm

Posted in Uncategorized

Voltmeter, Ampermeter, 5 digit 7 segment, my own code

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Few years back I purchased low cost (range of 100€) Power Supply HY3005D, rated for 30V and 5A. Just after few weeks I started to dislike the whole situation with LCD display w/o backlight and w/ really bad viewing angles. First option, for the reseller to give parts for an upgrade, didn’t happen. 2nd DIY backlight solved visibility at low light, but viewing angles remained. Not long ago I searched for voltmeters and ampermeters in this kind of form factor, to fit existing front panel.


After some measuring and searching on online marketplaces I came across a suitable option: (reseller: alice1101983 is recommended and reliable source of electronics kits& parts). I purchased 2x in a wish to change 2nd from Volt to Amp meter. Voltmeter works no problem. Vin is divided through a resistor ladder of 330 kΩ and 20 kΩ. These way input of 0 – 33 V is reduced to 20/(330+20) of Vin.  Knowing that voltage on shunt resistor definitely won’t reach limit I removed both resistors and shorted R3. At that time I didn’t look more into it. Comparison of multimeter and ampermeter on left side of Supply.

voltmeter comparison of multimeter and ampermeter values voltemeter backside

So ampermeter kind of works if you know you need to double the shown number. :) Well, not quite. As far I know resistor ladder can only divide not multiply the input voltage. The whole time I had in my mind I can just reprogram the microcontroller similarly (1|2) and correct the scaling. So I ordered 1 more. Also asked the seller (alice) to contact the possible manufacturer I got a negative replay. Today I decided to contact the supplier directly, first using TaoBao online page chat and then using their chat app. Thankfully I found ScreenTranslator that made installation little easier. No matter the unusual time (Friday night in China) supplier responded in English. Of coarse they didn’t gave me changed binaries. That would be awesome indeed. They forwarded me to forum post on this voltmeter. There is a 18bit ADC present (MCP3421, SOT23-6) which is quite nice for whole voltmeter price of 4$ (ADC cost about 1$/pcs @10pcs order).



Design conciderations:
Why not use I2C (pins 11 and 12) that is present in chip? Original bit-bangs I2C over pins 17 and 18.
Using SWIM pin as GPIO is not great for coding and debugging. Specially when this pin is utilized as part of communication (I2C). Download code -> start Debug -> disable Debug

1of5 digit duration  logic_one_frame_voltmeter_3.6V


Power supply uses 30 mΩ shunt resistor. Which results in 150 mV @ 5 A. I removed voltage divider resistors and shorted
ADC range is ±2.048 V. Using built in PGA 8x (Programable Gain Amplifier) changed max. voltage range presented to ADC input to 1200 mV. Decided for offset of 28 mA.

shunt resistor max. shunt voltage 160 mA 500 mA


Coding the segments and digits was easy. Replicating the I2C with similar timings to original needed more brain stretching. Also took me quite a lot of plugging and unplugging of ST-LINK. Last was to code the appropriate scale and possible offset. I did think about using input pin intended for push button, as a trigger for calibration but went with static definition usable in my case.  Also needed to unplug the programmer and plug in power supply.

Dropbox shared folder:
“project” folder


Written by luftek

February 28th, 2016 at 3:51 am

Posted in Make,pcb,Reuse

No Store page

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That is all there is to it. Adapter and cable are only available on eBay

Written by luftek

August 3rd, 2015 at 8:06 pm

Posted in Uncategorized

Smart watch from Weloop/GoClever

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Previous watches

I had problems with my Metawatch as did everybody else. Does freaking OLED displays didn’t last long (read comments on prev post). I returned it to TI and they refunded me in full. So I forget about the watches for a while, I wear a standard one (Casio) for a while. I broke this one in a bike crash in September 2015.

Weloop Tommy

Introduction to another smartwatch

I was reading daily news on my RSS feed and there is this article on HaD about an open source project OSSW by Krzysztof Szczesniak :

And I tought to myself this could be interesting. I am kind of interested in owning a watch that has an option/potential:

  • to be my silent alarm clock,
  • TOTP (“Timed One Time Password”)
  • lasts some 2 weeks of moderate use

I find mixed reviews about it, but trust that by contributing we can make it work, work better.
Read the rest of this entry »

Written by luftek

August 3rd, 2015 at 3:46 pm

Compact camera plastic gear repair, Canon A480

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I received a compact camera from the brother. He said he found it that way, broken or not working properly. With this he ment, lens mechanism was not extending and retracting as it should.

I had it stored for future repair time. Today I was again looking into it and found this page: (CHDK – Canon Hack Development Kit). I thought to myself, I would like to use this. But first I wanted to see if anything can be done to repair mechanism.

I used YT disassembly movie as a reference. I opened and removed the parts in this order: back plastic, screen assembly and then lens with sensor assembly. Had to desolder 2 ribbon cables (one for photo interrupter, one prob. for focus). Then I could split assembly.

(1st pic) Lens assembly has a motor with worm gear on it and 3 reduction gears. White gear on the right (You can see clearly how plastic gears fit together. Last one in the chain is long black one (broken).
(2nd pic) Broken gear with missing axis part. This gear is long, because the lens assembly extends outward. Replacements are sold on ebay for about 5€ and ship from far away, Hong Kong.
(3rd pic) 1,2 mm drill for making hole for replacement axis.
(4th pic) leg from diode rectifier used as axis.

Camera works now. Post with CHDK installed soon to come.

lens assembly broken gear, one side axis missing 1,25 mm drill axis transplant

Written by luftek

July 27th, 2014 at 8:05 pm

Posted in Repair

Worlde globe LED, night stand lamp

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I was thinking about adding light, to small world globe I have, for quite some time.
Yesterday I diffused 6 LEDs with sand paper and soldered 6 of them (parallel) into a small blob. After drilling the holes in globe holder, I ran wires GND and +V through. Today I added a 2×56 ohm resistors (about 28 ohm, and 0.5W) for limiting resistor and a micro usb port.
When not charging my phone I can learn countries of the world (in German :))

Also nice present for a small kid, who likes to have lights when going to bed.

6 star LED illuminated globe europe, globe micro usb and limiting resistors

Written by luftek

July 27th, 2014 at 7:25 pm

Posted in Make